East-West

1.6 Compare and contrast network topologies, architectures, and types

Traffic Flows

📘CompTIA Network+ (N10-009)

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East-West Traffic

In networking, traffic flows describe the direction that data moves across a network. There are two main directions you need to know for the CompTIA Network+ exam:

1. North-South Traffic – data moving in and out of a data center or network. (We covered this already.)
2. East-West Traffic – data moving inside the network, between servers or devices within the same data center or network segment.

Here we focus on East-West traffic.

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Definition

East-West traffic is the movement of data laterally within a network, from one server or device to another, without leaving the data center or local network.

• Direction: Horizontal (side-to-side)
• Scope: Internal, between servers, VMs, or storage systems
• Purpose: Often used for server-to-server communication, VM replication, storage access, and application workloads.

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Key Characteristics

1. Internal Communication
   • Happens inside a data center, cloud environment, or enterprise LAN.
   • Example: A web server sending data to an application server inside the same network.
2. High Traffic Volume
   • East-West traffic can be very heavy, especially in virtualized environments, because servers often communicate constantly.
   • Example: A database server exchanging large datasets with multiple application servers.
3. Low Latency Requirements
   • Since servers are often working together in real-time, fast and reliable connections are crucial.
4. Security Considerations
   • Firewalls and security devices may focus on North-South traffic, but East-West traffic still needs protection because malware or attackers can spread laterally inside the network.
   • Tools like internal segmentation firewalls or micro-segmentation are used to control it.

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Examples in IT Environments

1. Server-to-Server Communication
   • A database server sends query results to an application server.
   • An application server communicates with a caching server like Redis or Memcached.
2. Virtual Machines (VMs) Communication
   • VM1 communicates with VM2 in the same hypervisor cluster.
   • Often used in cloud environments like AWS or VMware.
3. Storage and Backup Traffic
   • Data moves between storage arrays and servers for backups or replication.
   • Example: SAN (Storage Area Network) traffic between servers and storage devices.
4. Clustered Services
   • Load balancers or clustered web servers exchanging session info.
   • Kubernetes pods inside the same cluster sharing data.

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Why It’s Important for Exams

• CompTIA Network+ may ask you to identify types of traffic flows, including East-West vs North-South.
• Key points to remember:
  1. East-West = internal, side-to-side
  2. North-South = entering or leaving the network
  3. Security and network design must consider lateral movement of data
  4. East-West traffic is common in modern data centers and cloud environments

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Visual Understanding

[Server A] <--> [Server B] <--> [Server C]
      ^          ^         ^
      |          |         |
  East-West Traffic inside the network

• Here, data is moving between servers horizontally inside the network.
• No traffic is leaving the data center; that would be North-South.

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✅ Exam Tip: If a question mentions lateral server communication, VM-to-VM data, or internal data center traffic, the answer is East-West traffic.

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